The research I propose to undertake involves the detailed investigation of structure, binding properties and transport function of bovine serum high-density lipoprotein (BHDL). In the work on BHDL structure, the experiments I propose to carry out on apo-lipoprotein behavior in solution, amino acid distribution in apo-lipoprotein fragments, interaction of apo-lipoproteins and their fragments with lipids, and the systematic investigation of the perturbation of BHDL structure by chemical and mechanical means, in particular the use of fluorescence techniques, are new approaches to the problem of high density serum lipoprotein structure, and are expected to contribute significantly to this area of research. A general understanding of lipoprotein structure and protein-lipid interactions in these relatively simple systems would be extremely important for the understanding of biological membranes. Another objective of this work is the elucidation of the transport function of BHDL beyond the lipid-carrier role that has traditionally been attributed to serum lipoproteins. The quantitative studies which I propose to carry out on BHDL binding of non-polar molecules, hydrophobic anions, hydrophilic molecules, various drugs, and hormones, using ultracentrifugal and spectroscopic techniques, are completely new investigations of lipoprotein properties. This work, together with experiments on BHDL binding-competition with serum proteins and interaction with membranes, should contribute to the understanding of the entire transport system in mammalian serum, and to the area of cardiovascular diseases.